Could it soon be game over for the Fortnite craze?

Yes, Fortnite game tournements fill stadiums, such as this one in Los Angeles earlier this year

It is a question that millions of parents want answered: will the wildly popular online survival battle game Fortnite soon lose its grip on the attention of their school-age children?

Much of the video game industry is also wondering whether the Fortnite balloon has popped, or is simply leaking air, after the first disappointing revenue data since the game's release last year, with experts saying its publisher Epic Games needs to put these doubts to rest if it is to succeed in its expansion plans.

Fortnite's popularity took off last year after the release of a free "battle royale" version that lets up to 100 players vie to be the last character standing on ever-shrinking terrain. Dropped onto the battlefield with nothing, players have to scrounge for weapons as the fight for survival begins.

Although the game is free, Epic Games had been successful in getting players to pay for goodies, which is its main revenue stream.

As of July the game had brought in more than a $1 billion in revenue.

But that data also gave analysts cause for concern that the Fortnite juggernaut may have tripped: revenue edged only 2 percent higher in July from the previous month.

It was a lacklustre response to the recently launched paid "battle pass" that offered players new equipment and outfits for avatars, raising questions about how much longer Epic Games can keep players shelling out money for what are essentially cosmetic changes to the game.

"Epic Games has made a lot of mistakes which could knock them from their peak, players could get tired if the game doesn't evolve and there is too much cosmetic" change, said Frederic Gau, president of Gozulting consulting firm.

Epic Games has also bet on eSports to reinforce the popularity of Fortnite, investing nearly $100 million in such video game competitions.

"One hundred million dollars of cash prizes seems a lot but prizes for each competition are not that" large, said Andrew Kitson, head of telecoms, media and technology industry research at Fitch Solutions.

- China ally -

Enabling the popularity of Fortnite is the fact it is available on different game consoles plus smartphones. For smartphones, it first launched for iPhone, then a few weeks later on Android, the operating system used on 85 percent of smartphones and particularly dominant in Asia.

"Android can provoke two different effects," said Laurent Michaud at IDATE Digiworld, a think tank and consultancy specialising in the internet, telecommunications and media sectors.

"It can boost other platforms or create its own proper segment, because often is is different players who play," he said.

China also offers enormous potential for growth, both in terms of smartphone players and as well as eSports, with the Chinese giant Tencent having already pre-registered 10 million players.

"Smartphones represent now 50 percent of global video game revenue and China represents half of that market," said Michaud. "Today the Chinese play mostly on smartphones."

Tencent, which is a big publisher of smartphone games as well as being behind the WeChat messenger, holds 40 percent of Epic Games.

Having Tencent behind it is a major advantage for penetrating the Chinese market.

"A success in China will show whether Fortnite will continue growing as a game for the general public," said Gau.

"It could also help enormously in it developing in eSports. It could either cause it to explode or steal its momentum elsewhere -- it's a bet."

But analysts say Epic Games has yet to address its major fault -- that Fortnite doesn't have sufficient variety compared to its principal online rivals, in particular eSport stars Dota2 and League of Legends which regularly reinvent themselves.

Kitson at Fitch Solutions said he thinks Fortnite is a one dimensional game, as were some older games that were still able to build a player community.

"Fortnite is not a commercial failure but not a long term shot," he told AFP. "But Epic Games can learn a lot from it to make a better one next time."

But even if Epic Games rushes out a new version of Fortnite -- the battle royale version was its second -- the consultant Gau sees another problem: "for many it is their a second game".

He said analysts will be looking closely if the sales of FIFA football and Call of Duty first-person shooter franchises hold up as well as in previous years, because "that wouldn't be a good sign for Fortnite as players are returning to their favourite game."